Answers

To get to Academia you have to complete the Sunleth Waterscape 300AF and Yaschas Massif 1X AF. After you finish each you will be taken to The Void Beyond. After the second time you leave you will have Academia 400 AF listed on the map.

When you arive at Sunleth you have to do the fight against the Flan. Afterwards, the characters mention following the mini Flans to find out something. The first fragment is in the Southernmost part of the map and it will take you to the Coliseum. The gate is near where you got the artefact. After the cutscene in the Coliseum you return to Sunleth. Now head to the far right of the map and you will get another artefact. The gate is at the top of the map. This will take you to the Archylte Steppe. From here you go to the top of the area which is the Nomad's Camp. Here you will get two missions to prove your worth. The first mission is a fight and the second is gathering wool from sheep. after you finish the two missions you will be able to change the weather. This is dictated by two levers that can be opperated one at a time. Both up is Cloudy weather, both down is Sunny, left up/right down is Rainy, and left down/right up is Stormy. The monsters will change in each weather so be careful. When you change the weather the camera will show you where the boss is, you will not be able to get to him in Sunny weather. After you kill the boss you can go back to Sunleth and you will be able to kill the Flan for good.